1. Field of the Invention
The invention relates to a pharmaceutical form having a separating layer.
2. Description of the Related Art
EP 0 088 951 A2 describes a process for the coating of pharmaceutical forms by means of a coating agent dispersed in water. For the redispersion of carboxyl group-containing (meth)acrylate copolymers from powders to give dispersions, the partial neutralization of the carboxyl groups is recommended. Salt formation of the acidic groups takes place by reaction with a base. Suitable bases are alkalis, such as, for example, sodium hydroxide solution, potassium hydroxide solution, soda, potash, sodium bicarbonate, trisodium phosphate, trisodium citrate or ammonia or physiologically tolerable amines, such as triethanolamine or tris(hydroxymethyl)aminomethane. A degree of neutralization of 0.1 to 10% by weight of the carboxyl groups contained in the copolymer is favourable with respect to redispersion.
WO 2004/096185 describes a pharmaceutical form and a process for its production. The pharmaceutical form is coated with an anionic (meth)acrylate copolymer which can be partially neutralized if required. In order to prepare a solution of the anionic copolymer, a partial or complete neutralization of the acid groups is usually necessary. The anionic copolymer can, for example, gradually be stirred into water in a final concentration of 1 to 40% by weight and can be partially or completely neutralized in the course of this by addition of a basic substance such as, for example, NaOH, KOH, ammonium hydroxide or organic bases such as, for example, triethanolamine. It is also possible to employ a powder of the copolymer, to which a base, for example NaOH, has already been added during its preparation for the purpose of (partial) neutralization, such that the powder is an already (partially) neutralized polymer. The pH of the solution is usually over 4, e.g. in the range from 4 to about 7.
WO 2005/007139 describes multiparticulate pharmaceutical forms, comprising mucoadhesively formulated peptide or protein active compounds. The application mentions that a separating layer can be applied between active compound-containing and intestine-soluble copolymer layer, which serves for the separation of active compound and coating material for the purpose of the prevention of interactions. This layer can consist of inert film-forming agents (e.g. HPMC, HPC or (meth)acrylic acid copolymers) or, for example, talc or another suitable pharmaceutical substance. Likewise, combinations of film-forming agents and talc or similar substances can be used. It is also possible to apply a separating layer of partially or completely neutralized (meth)acrylate copolymer dispersions. The separating layer can consist of the same or another mucoadhesive polymer as in the underlying matrix layer. Possible interactions or incompatibilities of the active compound or of the mucoadhesive polymer with the film-forming (meth)acrylate copolymer layer can be encountered in this way.
It has been attempted in the case of an intestinal juice-soluble coated pharmaceutical form to achieve a high reproducibility of the active compound release, in that on reaching specific pH coatings dissolving as rapidly as possible developed. However, the present invention starts out from an alternative concept.